Regenerative furnace



y 1941- s. KNEA SS, JR 2,248,573

REGENERATIVE FURNACE Filed Maw 20, 1940. 2 Sheets-Sheet 2 INVENTOR STRICKLAND KNEA-S'S JR W Q. W

ATTORZVEY Patented July 8, 1941 V 2,248,573 REGENERATIVE FURNACE Strickland Kneass, J r., Worcester, Mass, assignor to Morgan Construction Company, Worcester,

Mass, a corporation of Massachusetts Application May 20, 1940, Serial No. 336,105

10 Claims.

This invention relates to regenerative furnaces, and more particularly to furnaces of the type having two series of ports located on opposite sides of a heating chamber, one serving for the admission of fuel and air, and the other serving for the escape of the gaseous products of com-' bustion. Upon reversal of the furnace, the functions of the respective series of ports are reversed.

Furnaces of this type are commonly used for the melting of glass, and since the material is charged at one end of the furnace and travels ensure a zone of the desired uniform temperature between each pair of oppositely located ports. The reasons for this have not been clearly understood heretofore, and no suitable solution for the problem has been proposed.

It is accordingly the main object of the invention to provide a regenerative furnace in which a plurality of zones of different temperatures are established between pairs of opposing ports and the temperature in each zone is maintained substantially uniform.

It is a further object of the invention to provide in combination with a regenerative furnace of known construction a novel arrangement of control apparatus whereby a plurality of zones of different and substantially uniform temperatures may be established and maintained between pairs of opposing ports, and whereby efficient combustion of the fuel may be' assured.

It is a further object of the invention to provide a novel and effective method of operating a regenerative furnace and maintaining desired temperature conditions in zones located between pairs of opposing ports.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts and the steps of the process set forth in the specification and covered by the claims appended hereto.

Referring to the drawings illustrating one embodiment of the invention and in which like reference numerals indicate like parts.

Fig. 1 is a diagrammatic plan view of a regenerative glass-melting furnace and associated automatic .gregiilating apparatus, certain pjarts being shown in section for clearness of illustration; 7

Fig. 2 is a section on the line 2-2 of Fig. 1;

Fig. 3 is a detail in section of a normally open duplex valve, shown in its open position;

Fig. 4 is a view similar to Fig. 3, but showing the valve in its closed position;

Fig. 5 is a detail in section of a normally closed duplex valve, shown in its closed position; and

Fig. 6 is a view similar to Fig. 5, but showing the valve in its open position.

The embodiment illustrated comprises a glassmelting furnace II] of well-known construction having the usual dog house II at one end for the introduction of the batch of raw materials. At opposite sides of the furnace are rows of ports I2, I2 with which fuel burners I4, I4 are associated, there being two burners for each port. Fuel is supplied to the burners by means of main pipes I5, I5 and branch pipes I6, It, each branch pipe connecting its corresponding main pipe to' two ofthe burners. .The main pipes are provided with valves I8, I8, and the branch pipes are provided with valves I9, I9. The ports I2, I2, serve to connect the furnace with rows of regenerators 20, 20' (Fig. 2) having the usual checkerwork therein, the regenerators communicating with ejectors 2|, 2| comprising upright nozzles 22, 22' surrounded by casings 23, 23' from which stacks 24, 24 extend upwardly above the nozzles. The stacks are provided with valves or dampers 25, 25. The casings 23, 23' are connected by means of branch ducts 21, 21 to main ducts 28, 28, the main ducts being supplied with air under pressure from any suitable source.

It will now be understood that with the burners I4 in operation, the valve I3 will be open, and the valves I6 will be adjusted either manually or automatically (in known manner) to provide a desired distribution of the fuel among the ports I2. The valve It will be closed, the dampers 25 will be closed, and the dampers 25 will be open. Air for combustion will be supplied from the main duct 28 through the branch ducts 21' to the casings 23, and because of the closed dampers 25 this air will be compelled to flow downwardly through the nozzles 22' to the'regenerators 20' and thence through the ports I2 to the furnace. Air will also flow from the main duct 28 through the branch ducts 21 to the casings 23, and since the dampers 25 are open this air will escape upwardly through the stacks 24, producing an ejector action which will create a suction in the nozzles 22.

This will cause the hot gases from the furnace to flow outwardly through the ports 12 and the regenerators 20, and thence upwardly through the nozzles 2, whereupon these gases will be entrained by the ejection air and discharged from the stacks 24. The regenerators will absorb heat from the hot gases, and the regenerators 23' will give up heat to the combustion air. To reverse the furnace, the valve l3 and the dampers 25 will be opened, and the valve I8 and the dampers 25 will be closed. This will place the burners id in operation, and the flow through the furnace will be in the opposite direction, the air from the duct 28 being used for combustion, and the air from the duct 28 being used for ejection of the gases.

The pressure in the main duct supplying the air for ejection of the gases is preferably regulated automatically in accordance with the pressure in the furnace ill, to maintain the furnace pressure substantially constant. Furthermore the pressure in the main duct supplying the air for combustion or the fuel is preferably maintainedsubstantially constant by automatic mechanism in order to facilitate control of combustion in a desired manner. For this purpose the main ducts 28, 28' are provided with dampers 3D, 38 arranged to be actuated by reversible hydraulic motors 3|, 3%. Two conduits 32 are connected to opposite ends of the motor 3!, and two conduits 32' are connected to opposite ends of the motor 3!. Conduits 34, 34 lead from the main ducts 28, 28' respectively, at points beyond the dampers 39, 3a, to a three-way valve 35 from which a conduit 36 leads to an automatic reguiator 38 of well-known construction. This regulator includes a flexible diaphragm 39 to which the air pressure from the conduit 36 is applied, this diaphragm being connected to a pivotally mounted nozzle 40 supplied with a suitable pressure fluid, such as oil, through a pipe 41, and arranged to direct the fluid to one or the other of two conduits 1-2. These conduits 42 are connected to the conduits 32 through a normally open duplex valve 43 and to the conduits 32" ing fluid pressure to the piston through an opening 54 in the end of the casing opposite the spring, the piston can be forced to the other end of the casing, as shown in Fig. 4, closing communication between the ports. The valve '44, as disclosed in Figs. 5 and 6,. comprises a casing 56 having a slidable piston 51 therein formed with two axially spaced circumferential grooves 58 and 59. The piston 57 is normally held at one end of the casing by means of a spring 6i, as shown in Fig. 5, with the grooves 58 and 53 out of registration with opposed pairs of ports 62 and 63. By applying fluid pressure to the piston through an opening 64 in the end of the casing opposite the spring, the piston can be forced to the other end of the casing, as shown in Fig. 6, bringing the grooves into registration with the ports. In order that the movements of the valve pistons may be readily controlled, the openings 5d and 64 are connected by branch conduits 66 (Fig. 1) to a main pipe 67. By mean of a all) "to the main pipe 67.

7 nace port.

three-way valve 68 the pipe 61 may be connected either to a pressure pipe 69 or to an exhaust pipe '19, the pipe 69 being supplied with pressure fluid from any suitable source. With the threeway valve 68 in the position indicated in Fig. 1, the pipe 51 will be under pressure, the valve 43 will be closed, and the valve 54 will be open. Under these conditions, the regulator 38 will control the damper 3B in accordance with the pressure in the duct 28 and maintain said pressure substantially constant.

In order to control the furnace pressure there is provided a regulator ll similar in construction to the regulator 33 and comprising a flexible diaphragm '52 which is subjected by means of conduits T3 to the pressure differential between the interior of the furnace I0 and the atmosphere adjacent the furnace. This diaphragm is connected to a pivotally mounted nozzle 15 supplied with a suitable pressure fluid, such as oil, through a pipe i6, and arranged to direct the fluid to one or the other of two conduits I7. These conduits are connected to the conduits 32 through a normally closed duplex valve 19 (similar to the valve 44) and to the conduits 32 through a normally open duplex valve (similar to the valve 43). Branch conduits 8| connect the valves 19 and 80 Thus with the main pipe 6'! under pressure, as shown in Fig. 1, the valve 19 will be open, the valve 80 will be closed, and the regulator II will control the pressure in the furnace Iii by actuating the damper 3G.

The air flow in the branch ducts 2T, 21 is controlled in such a manner as to maintain a desired ratio between the supplies of fuel and of cornbustion air at each furnace port along one side of the furnace, and to distribute the outflowing gases among the ports on the other side of the furnace in a manner corresponding to the distribution of the fuel and air among the inlet ports. I have discovered that in this manner it is possible to establish and maintain zones of different and substantially uniform temperatures between pairs of opposing ports. For this purpose sliding gates or dampers 83, 83' (Fig. 2) are provided in the branch ducts 27, 21', these gates being actuated by means of reversible through a pipe 92, and arranged to direct the fluid to one or the other of two conduits 93.

These conduits are connected through a normally open duplex valve (similar to the valve 43) to a pair of conduits 96 which lead to opposite ends of one of the motors B4. The conduits 93 are also connected through a normally closed duplex valve 91 (similar to the valve 44) to a pair of conduits 95' which lead to opposite ends of the corresponding motor 84. Branch conduits 98 connect the valves 95 and 91 to the main pipe Bl.

The diaphragm 8'! is subjected to a pressure differential which is a function of the rate of supply of combustion air to the corresponding fur- For this purpose conduits I00, I00 lead from the casings 23, 23' to a threeway valve IOI, and-conduits I02, I02 lead from the interior of the nozzles 22, 22 to a three-way valve I03. Conduits I04 and I05 lead from the valves IOI and I03 respectively to opposite sides of the diaphragm 81. With the valves positioned as shown in Fig. l, the diaphragm will be controlled by the combustion air flowing into the corresponding casing 23, whereas if the valves IOI and I03 are reversed the diaphragm will be controlled by the combustion air flowing into the casing 23.

The diaphragm 88 is subjected to a pressure differential which is a function of the rate of supply of fuel to the corresponding furnace port. For this purpose the branch fuel pipes I6, I6 are provided with orifice plates I01, I01. Conduits I08, I08 lead from these branch pipes, anterior to the orifice plates, to a three-way valve I09, and other conduits H0, H0 lead from the branch pipes, posterior to the orifice plates, to a three-Way valve III. Conduits H3 and H4 lead from the valves I09 and III respectively to opposite sides of the diaphragm 88. With the valves positioned as shown in Fig. l, the diaphragm will be controlled by the fuel flowing in the corresponding branch pipe I6, whereas if the valves III and I09 are reversed the diaphragm will be controlled by the fuel flowing in the corresponding branch pipe I6.

The forces produced by the loading of the respective diaphragms 81 and 88 are opposed through the lever mechanism 89, and by swinging the nozzle 9I slightly in one direction or the other they regulate the motor 84. or 84 (as the case may be) to control the flow of combustion air in accordance with the flow of fuel. By adjusting the lever mechanism, the ratio of air to fuel may be varied as desired. Of course, the several regulators 85 may be adjusted for different fuel-air ratios, so that the combustion conditions in the respective furnace zones may be independently controlled.

The operation of the invention will now be apparent from the above disclosure. With the parts positioned as shown in Fig. 1, the burners I4 will be in service, and valve I8 will be closed to prevent fuel flow to the burners I4. Valve I8 will be open, and valves I9 will be adjusted to distribute the fuel in a desired manner among the several furnace ports I2. Regulator 38 will control the damper 30 and maintain a substantially constant air pressure in the duct 28. Each regulator 85 will control the corresponding air gate 83 in. accordance with the rate of fuel flow to the corresponding furnace port. The valves 95 being closed, the air gates 83 will be held fixed in the positions which they occupied at the time of the last furnace reversal. Thus the air for ejection purposes will be distributed from the duct 28 among the several casings 23 in substantially the same proportions as the combustion air was distributed prior to the last furnace reversal. This air will flow upwardly through the stacks 24, and by creating a suction in the nozzles 22 it will draw the gaseous products of combustionl outwardly through the ports I2 and the regenerators 20. These gases will be entrained by the ejection air "and thus discharged from the stacks. The total flow of the ejection air will be controlled by the regulator II through the medium of the damper 30 so as to maintain a predetermined pressure in the furnace I0. The combustion air will absorb heat from the regenerators 20, and the regenerators 20 will absorb heat from the outwardly flowing hot gases.

To reverse the furnace, the valve I8 will be closed, stopping the fuel flow to the burners I4.

Dampers 25 will be opened and dampers 25 closed, thus reversing the air flow through the furnace. At the same time the three-way valves '35, 68, IOI, I03, I09 and III will be reversed. Then the valve I8 will be opened, placing the burners I4 in service. The reversal of the valve '68 will relieve the pressure from the pipe 61, so

that the valves 43, and 95 will open, and the valves 44, I9 and 91 will close. The valves I9 will control the distribution of the fuel among the several furnace zones, and they will preferably be adjusted to provide the same distribution as the corresponding valves I9. Regulator 38 will now control the damper 30 and maintain a constant pressure in the duct 28, while regulator 'II will control the damper 30 and maintain a constant pressure in the furnace I0. Each regulator will control the corresponding air gate 83 and maintain the flow of combustion air in a desired ratio to the flow of the fuel. The closed valves '91 will hold the air gates 83 fixed in the positions which they occupied when the furnace was reversed. Consequently the distribution of the ejection air among the several casings 23 will be substantially the same as the distribution of the uniform temperature in the furnace, and to control the temperatures in the respective zones v independently.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

-1. A regenerative furnace comprising a heating chamber having two series of ports on opposite sides thereof, a burner associated with each port, means to supply fuel to the burners on opposite sides of the heating chamber alternately and to distribute the fuel among the burners in such a manner as to establish zones of difierent temperatures between pairs of opposite ports, an ejector connected to each port, means to supply air to each ejector, adjustable means associated with each ejector whereby the air may be either directed inwardly through the corresponding port to serve'as combustion air or caused to serve as'ejection air by entraining and withdrawing the gaseous products of combustion through the corresponding port, a damper to control the air supply to each ejector, automatic regulators to control the dampersat the inlet side of the heating chamber in accordance with the rate of supply of the fuel to the corresponding burners, and means operable automatically to hold the dampers at the outlet side of the heating chamber fixed in the positions which they occupied peratures between pairs of opposite ports, an ejector connected to each port, means to supply air toeach ejector, adjustable means associated with each ejector whereby the air may be either directed inwardly through the corresponding port to serve as combustion air or caused to serve as ejection air by entraining and withdrawing the gaseous products of combustion through the corresponding port, a damper to control the air supply to each ejector, a motor connected to each damper, a regulator for each pair of corresponding motors and responsive to the rate of supply of fuel to the corresponding zone, means to connect the regulators to the motors at the inlet side of the heating chamber, and means tovhold the motors at the outlet side of the heating chamber stationary in the positions which they occupied at the time of the last reversal of the furnace.

3. A regenerative furnace comprising a heating chamber having two series of ports on opposite sides thereof, a burner associated with each port, means to supply fuel to the burners on opposite sides of the heating chamber alternately and to distribute the fuel among the burners in such a manner as to establish zones of different temperatures between pairs of opposite ports, an ejector connected to each port, a main air duct on each side of the heating chamber, a branch duct connecting each ejector to the adjacent main duct, adjustable means associated with each ejector whereby the air delivered thereto through the branch duct may be either directed inwardly through the corresponding port. to serve as combustion air or caused to serve as ejection air by entraining and withdrawing the gaseous products of combustion through the corresponding port, a damper in each branch duct, a motor connected to each damper, a regulator for each pair of corresponding motors and responsive to the rate of supply of fuel to the corresponding zone, means to connect'the regulators to the motors at the inlet side of they heating chamber, means to hold the motors at the outlet side of the heating chamber stationary in the positions which they occupied at the time of the last reversal of the furnace, and means to regulate the supply of air to the main duct atthe outlet side of the heating chamber in accordance with the pressure within the heating chamber.

4. A regenerative furnace comprising a, heating chamber having two series of ports on opposite sides thereof, a burner associated with each port, meansto supply fuel to-the burners on'opposite sides of the heating chamber alternately and to distribute the fuel among the burners in such a manner as to establish zonesof different temperatures between pairs of opposite ports, an ejector connected to each port,, a main air duct on each side of the heating chamber, a branch duct connecting each ejectorto;

the adjacent main duct, adjustable means associated with each ejector whereby the air delivered thereto through the branch duct may be either directed inwardly through the corresponding port to serve as combustion air or caused toserve as ejection air by entraining and Withdrawing the gaseous products of combustion through the corresponding port, a damper in each branch duct, a motor connected to each damper, a regulator for each pair of corresponding motors and responsive both to the rate of supply of fuel to the corresponding zone and to the rate of supply of combustion air to the corresponding zone, means to connect the regulators to the motors at the inlet side of the heating chamber, means to hold the motors at the outlet side of the heating chamber stationary in the positions which they occupied at the time of the last reversal of the furnace, means to maintain a; substantially constant air pressure in the main duct at the inletside of the heating chamber, and means to regulate the supply of air to the main duct at the outlet side of the heating chamber in accordance with the pressure within the heating chamben 5. The method of operating a regenerative furnace-having a heating chamber with two series of ports on opposite sides thereof comprising the steps of supplying fuel to the ports of each series alternately, distributing the fuel among the ports insuch a manner as to establish zones of predetermined temperatures between pairs of opposite POI'tS SLlPDIYlIlg combustion air to the ports of each series alternately, distributing the air among the portsat the inlet side of the heating chamber in a manner similar to the distribution of the fuel, withdrawing gaseous products of combustionthrough the ports of each series alternately, and distributing the said gaseous products of combustion among the ports at the outlet side of the heating chamber in substantially the same relative proportions as the combustion air is distributed among the ports at the inlet side of the heating chamber.

6. The method of operating a regenerative furnace having a heating chamber with two series of ports on opposite sides thereof comprising the steps of supplying fuel to the ports of each series alternately, distributing the fuel among the ports in such a manner as to establish zones of predetermined temperatures between pairs of opposite ports, supplying combustion air at a pressure above atmospheric to the ports of each series alternately, distributing the air among the ports at theinlet side of the heating chamber in a manner similar to the distribution of the fuel, subjecting the two series of ports to sub-atmospheric pressures alternately and thereby withdrawing the gaseous products of combustion through the ports, and regulating the sub-atmospheric pressures applied to the ports at the outlet side of the heating chamber to distribute said pres- :sures in substantially the same relative proportions as the combustion air is distributed among the ports at the inlet side of the heating chamber.

7. The method ofoperating a regenerative furnace having a heating chamber with two series of ports on opposite sides thereof and ejectors connected to the ports comprising the steps of supplying fuel to the ports of each series alternately, distributing the fuel among the ports in such a manner as to establish zones of predetermined temperatures between pairs of opposite ports, supplying combustion air at a pressure above atmospheric to the ports of each series alternately, distributing the air among the ports at the inlet side of the heating chamber in a manner similar to the distribution of the fuel, supplying ejection air at a pressure above atmospheric to the ejeotors on opposite sides of the heating chamber alternately and thereby withdrawing the gaseous products of combustion through the ports, and distributing the ejection air among the ejectors at the outlet side of the heating chamber in substantially the same relative proportions as the combustion air is distributed among the ports at the inlet side of the heating chamber.

8. The method of operating a regenerative furnace having a heating chamber with two series of ports on opposite sides thereof, each port having an ejector connected thereto and provided with adjustable means whereby air supplied to the ejector may be either directed inwardly through the corresponding port to serve as combustion air or caused to serve as ejection air by entraining and withdrawing the gaseous products of combustion through the corresponding port comprising the steps of supplying fuel to the ports of each series alternately, distributing the fuel among the ports in such a manner as to establish zones of predetermined temperatures between pairs of opposite ports, supplying air to the ejectors at a pressure above atmospheric, regulating the air supply to each ejector at the inlet side of the heating chamber in accordance with the rate of supply of fuel to the corresponding port, distributing the air among the ejectors at the outlet side of the heating chamber in substantially the same relative proportions as the air is distributed among the ejectors at the inlet side of the heating chamber, and regulating the total supply of air to the ejectors at the outlet side of the heating chamber in accordance with the pressure within the heating chamber.

9. A regenerative furnace comprising a heating chamber having two series of ports on opposite sides thereof, a burner associated with each port, means to supply fuel to the burners on opposite sides of the heating chamber alternately and. to

distribute the fuel among the burners in a desired manner, means to supply combustion air at a pressure above atmospheric to the two series of ports alternately, automatic regulators arranged tocontrol the flow of combustion air to the ports at the inlet side of the heating chamber in accordance with the rate of supply of fuel to the corresponding ports, means to subject the two series of ports to sub-atmospheric pressures alternately and thereby withdraw the gaseous products of combustion through the ports, and means operable automatically upon reversal of the furnace to effect a distribution of the said gaseous products among the outlet ports in substantially the same relative proportions as the combustion air is distributed among the inlet ports.

10. A regenerative furnace comprising a heating chamber having two series of ports on opposite sides thereof, a burner associated with each port, means to supply fuel to the burners on opposite sides of the heating chamber alternately and to distribute the fuel among the burners in a desired manner, means to supply combustion air at a pressure above atmospheric to the two series of ports alternately, automatic regulators arranged to control the flow of combustion air to the ports at the inlet side of the heating chamber in accordance with the rate of supply of fuel to the corresponding ports, ejectors connected to the ports, means to supply ejection air to the ejectors on opposite sides of the heating chamber alternately and thereby withdraw the gaseous products of combustion through the ports, and means operable automatically upon reversal of the furnace to effect a distribution of the ejection air among the ejectors at the outlet side of the heating chamber in substantially the same relative proportions as the combustion air is distributed among the inlet ports.

STRICKLAND KNEASS, JR. 

